Part of his sound is probably direct to the PA mixer. Some groups use a combination of a miked cab, some effects processor and direct signal. Most of the deep bass produced by live concerts is EQed from the PA and not from an onstage rig. The soundman will adjust things to get a certain sound.

When something goes to video, its remixed/EQed in a studio to bring out different frequencies so it sounds good on cheap TV speakers and Hi-Fi Stereo equipment. Overdubs do sometimes occur on live concerts also. Have you ever seen a video where someone is playing a set of notes but a different set of notes is heard?